When clamping work pieces by means of vises or clamps it is very often time consuming or inconvenient to open and close jaws using standard screw and nut tighteners because of the large number of turns required to move the jaws large distances. For example clamping a board in a wood working vise, first in a two inch width and then in a ten inch width, sequentially and repeatedly as is done often in finishing operations, extends the time required for the job and contributes to operator fatigue. It would therefore be desirable to be able to position the jaws quickly in either a narrow or wide opening by merely sliding the jaws to the desired position and tightening with only a few turns. This has been done in the case of the woodworking vise, wherein a longitudinally split nut can be disengaged by rotating to the left a turn, sliding the vise jaws to a desired position, re-engaging the jaws with a rotation of the screw to the right, and then tightening the work in place. This particular type of wood working vise has been in reliable use for many years but has a drawback that prevents its application to other than operation in the horizontal plane; the longitudinal split nut relies on gravity to open the nut for sliding the jaws into position before tightening. Another example of a quick disconnect threaded fastener is found in U.S. Pat. No. 2,828,662 wherein the concept of segmented threaded fasteners has been applied to individual nut and bolt assemblies as well as to C-clamps and other fastener applications. While the mechanism of said patent will work in any position, it appears to be somewhat complex and to be limited in thread engagement area. The present invention will be shown to provide some advantages over the state of the art.